Continuous rail track circuits



lHI

III 23 le *A TRANSMWTER RECEIVER E2 El FISI De. 19, `1967 c. s. wILcox 3,359,416

CONTINUOUS RAIL TRACK CIRCUITS Filed March 29, 1965 2 Sheets-Sheet 1 I fr Lu 5N O 5 T O U- u.) V Lu Lu LD n: fr N N Lu Q t E E Y LL I-`- X V ff I E w N I" I u A m I i lo If ff Lu 5 cv LE m I 5 c; E U Q E E LL q -I HIS ATTORNEY C. S. WILCOX CONTINUOUS RAII.- TRACK CIRCUITS Dec. 19, 1967 2 Sheets-Sheet 2 HIS ATTORNEY Filed March 29, 1965 United States Patent O 3,359,416 CONTINUDUS RAIL TRACK CIRCUITS Ciinton S. Wilcox, Rochester, N.Y., assignor to General Signal Corporation, Rochester, N.Y., a corporation of New York Filed Mar. 29, 1965, Ser. No. 443,459 4 Claims. (Cl. 246-34) ABSTRACT OF THE DISCLOSURE A high frequency track circuit is provided which has a source of high frequency energy connected across the track rails at one location land has a relay connected across the track rails at another location through an amplifier and iilter and through induction coils which lare connected in series with wires secured to the respective track rails. The coils are disposed with their magnetic axes normal to a magnetic lield set up by current flowing in the track rails. The relay is thus energized jointly by direct wire connection through the track rails to the source of energy and by energy induced in the coils by current flowing in the track rails.

This invention relates to track circuits `for railroads, and it more -particularly pertains to double-rail alternating current track circuits for a stretch of -continuous rail railway track.

The present practice of many railroads of using continuous rails without rail joints, makes it difficult to p-rovide positive demarcation of the ends of track sections for signaling purposes within a continuous r-ail stretch of track. Where insulated joints can be used to mark the ends of track sections which have track circuits associated therewith, the marking of the limits of the sections are definite, but if audio 4frequency track circuits are used, lfor example, without rail joints to mark the ends of the sections, it is ditiicult to energize a track relay in one section when a shunt is applied across the track rails by a train which is a short distance within an adjoining section.

The present invention provides la means for accurately marking the relay ends of track sections in continuous rail alternating current track circuits without the use of rail joints. The track circuits are fed from suitable sources of alternating current which are connected to the track rails at one end of the respective sections. These sources can be at designated audio frequencies. Suitable receiving means is provided at the other ends of the respective sections for receiving energy transmitted directly through the track rails as a difference of potential across the track rails at the receiving end of the section when no train is present, and this receiving apparatus is valso energized by potentials set up in inductance coils disposed at the respective receiving ends of the sections adjacent the respective track rails. These coils are disposed with their magnetic axes normal to the direction of current flow through the track rails. A potential is generated in these coils in accordance with increased current ow through the track rails of the associated track section caused by the shunting of the track rails by the presence of a train in -an adjoining track section.

The potential induced in the induction coils is applied to the receiving apparatus in the same direction as the potential received by direct connection to the track rails. Therefore, the receiver is at times energized substantially entirely by the interrail potential, at other times energized substantially entirely by the potential induced in the induction coils, and at other times is energized partly by interrail potential and partly by potential induced in the induction coils. It is thus possible, by proper selection of the number of turns on the induction coils, to provide that the receiving Iapparatus for a track circuit will receive ICC substantially the same degree of energization when the associated section is unoccupied and the adjoining section is occupied as when both of these sections are unoccupied.

An object of the present invention is to provide an alternating current track circuit in a continuous rail stretch of track that is instantaneously responsive to the movement of a train passed a point of connection across the rails of receiving means in the track circuit.

Another object of the present invention is to provide an alternating current track circuit in a continuous rail stretch of track that is instantaneously responsive to the movement of a train in either direction passed a point of connection across the track rails of receiving means in the track circuit.

Another object of the present invention is to provide, in a highway crossing protection system, a means, without the use of rail joints, for immediately detecting that a train has cleared the highway crossing when it passes a point of connection across the track rails of receiving means for receiving high frequency track circuit energy transmitted through a stretch of railway track extending through the highway crossing.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawings, and in part pointed out as the description of the invention progresses.

In describing the invention in detail, reference is made to the accompanying drawings wherein corresponding reference characters are used in the several figures to designate corresponding apparatus, and wherein:

FIG. l illustrates typical track circuits organized according to the present invention for a stretch of continuous rail trackway;

FIG. 2 illustrates schematically the manner in which the receiving apparatus of FIG. 1 is connected to the track rails;

FIG. 3 illustrates a modified receiving means for the track circuit provided according to the present invention;

FIG. 4 illustrates the application of the track circuits according to the present invention in a highway crossing control system; and

FIG. 5 is a sectional View of one of the track rails showing means for securing an induction coil to a track rail.

With reference to FIG. l, a system of wayside track circuits is illustrated for a continuous stretch of track having track rails 10 and 11 which are continuous rails without insulated joints. The stretch of track is divided into track sections A and B by the connection of transmitting and receiving apparatus to the track rails. Each section extends from a point of connection of a transmitter to the track rails to a next point of connection of a receiver to the track rails for the same frequency. Thus a frequency F1 Transmitter 12 is connected across the track rails 10 and 11 at points 13 and 14 respectively, and a frequency F1 Receiver 15 is connected across the track rails 10 and 11 at the points 16 and 17 respectively. The portion of the trackway between the point of connection of the F1 Transmitter 12 and the F1 Receiver 15 `can be considered as being track section B. The track rails of this section are included in series in a track circuit which is "fed by the F1 Transmitter 12 and wherein` the occupancy of the track circuit is detected at the wayside by the F1 Receiver 15. The F1 Transmitter 12 may be selectively connected across the track rails 10 and 11 at the points 13 and 14 in-accordance with the requirements of practice as is indicated by XX in the wire connecting the F1 Transmitter 12 to the point 13. Each of the transmitters preferably includes a suitable filter, such as a series filter, in its output connection to the track rails which offers a low impedance for transmission but a high impedance to the other frequencies transmitted through the track rails.

Similarly, an 'adjoining track section A has a track circuit wherein frequency F2 Transmitter 18 is connected across the track rails 111 and 11 at points 16 and 17 respectively and a frequency F2 Receiver 19 is connected across the track rails 10 and 11 at points 20 and 21 respectively.

The wayside circuits as shown in FIG. 1 can be used, for example, to register the condition of occupancy in advance of a train where the trains are equipped with receiving apparatus operable to receive the audio frequency currents in the track rails 10 and 11. Thus, if a train is travelling from left to right in the stretch of track illustrated in FIG. 1, and has entered section A, such train receives both the frequencies F1 and F2, if there is no train in advance in sections A and B. Frequency F1 is transmitted through section B and the portion of section A in advance of the train, and the frequency F2 is transmitted through section A in advance f the train. The reception of both frequencies F1 and F2 on the train provides an indication on the train that the sections A and B are both unoccupied in advance of the train. In a signaling system, the sections A and B could each be of a length comparable to the braking distance of a train travelling at its maximum speed permitted in the associated section. Frequency F1 Receiver 15 and frequency F2 Receiver 19 can be used at the wayside for selecting the approach control of the transmitters and for other purposes such as for selecting specific tones to be cornmunicated in a section occupied by a train.

With reference to FIG. 2, a system is illustrated for the connection of a typical Receiver 15 to the track rails 10 and 11 of FIG. l wherein the Receiver 15 is connected to the track rails and 11 through induction coils 22 and 23 respectively. These coils are disposed vertically fiange and the ball of the rail. Thus, the coils 22 and 23 are disposed with their magnetic fields normal to the magnetic field set up by energy flowing through the track rails from theV respective transmitters. Inasmuch as energy from a transmitter such as the F1 Transmitter 12 flows through the rails 10 and 11 in opposite directions respectively, the induction coils 22 and 23 are oppositely connected in a circuit connecting the F1 Receiver 15 to the track rails 10 and 1-1. This provides that the potential induced in the inductance coils 22 and 23 is of a polarity and phase to be in series with the interrail potential that is sensed at the point of connection of the inductance coils 22 and 23 to the track rails 10 and 11. Thus the frequency F1 Receiver 15 receives energy from the frequency F1 Transmitter 12 that is transmitted through the track rails 10 and 11, and the potential applied to the frequency F1 Receiver 15 is further increased over the interrail potential by the voltage induced in the inductance coils 22 and 23 due to the current flow from the frequency F1 Transmitter 12 through the track rails 10 and 11.

With reference to FIG. 2, the frequency F1 Receiver is illustrated as comprising a frequency F1 Filter 24, a suitable Amplifier 25, and an occupancy detection relay TR. The input from the track rails 10 and 11 is applied through the frequency F1 Filter 24 to the Amplifier 25', and an output of the Amplifier 25 is connected to the track relay TR. Thus the track relay TR is maintained picked up when the frequency F1 Transmitter 12 is active, provided there is no train within the section B. The track relay TR can be used to register conditions of occupancy for the general control of Wayside circuits, or for the visual indication of conditions of occupancy as is illustrated in FIG. 2. According to FIG. 2, the closure of front contact 26 provides an indication that the section B is unoccupied by the energization of an indicator lamp GE. If the track relay TR becomes dropped away because of occupancy of the section B, the circuit for the energization of the lamp GE is opened at front contact 4- 26, and a lamp RE is energized through back contact 26 to indicate occupancy of section B.

One mode of operation of the system according to FIG. 1 is that it is provided for eastbound traiic (to the right), and that the transmitters of frequencies F1 and 2 are normally inactive when the stretch of track is unoccupied. The approach of a train activates the transmitter at the end of the next section in advance of the section occupied by the train. Thus, for example, an eastbound train in the track section in approach of section A activates the frequency F2 Transmitter 18 to transmit frequency F2 through section A, and when the eastbound train enters the section A, the approach control apparatus (not shown) is effective to activate the frequency F1 Transmitter 12 at the exit end of section B.

With frequency F2 Transmitter 18 transmitting, and the section A unoccupied the frequency F2 Receiver 19 is energized and thus its track relay (not shown) is in its picked up position. The approach of an eastbound train to section A causes more current to iiow through the track rails of section A because of the shunt applied across the track rails 111 and 11 by the train, and also there is a drop in the interrail potential at the points 13 and 14 because of the train shunt. Because of the increased current iiow in the track rails, a higher voltage is induced in the induction coils 27 and 28 through which the frequency F2 Receiver 19 is connected to the track rails. Thus a substantially constant input is applied to the Receiver 19 right up to the time when the eastbound train directly shunts the track rails 1li and 11 at points 26 and 21 because the drop in interrail potential is compensated for by the increase in induced voltage in the induction coils.

When the forward axle of the eastbound train applies a direct shunt across the points 20 and 21 in the `rails 10 and 11, a track relay (not shown) becomes dropped aw-ay, and this relay is used to control apparatus not shown over a line circuit to start transmission of frequency F1 Transmitter 1S through section B. Thus it will be readily apparent that the track circuits are activated for another section in advance immediately upon the application of a direct shunt across the points 20 and 21 by an eastbound train, but not before that time, providing a definite location for the end of the track section as if such end had been marked according to prior practice by the use of an insulated rail joint.

With reference to FIG. 3, a modified form of the present invention is illustrated wherein a receiver 29 has two inputs, one of which comes directly from track rails 10 and 11, and the other of which comes from induction coils adjoining the track rails 10 and 11. Track relays TRA and TRB are controlled by the respective inputs to receiver 29, and the picking up of either of these relays is an indication that the associated track section is unoccupied.

With reference to FIG. 3, the track relay TRA is energized by the interrail potential yacross the track rails 10 and 11 through a suitable frequency F2 Filter 30, the output of which is connected to a suitable Amplifier 31, which in turn provides an output for the energization of the track occupancy detector relay TRA. Thus relay TRA is in its picked up position when no train is in the associated track circuit, and in accordance therewith the lamp GE1 becomes energized through front contact 30 of relay TRA to register an indication that the associated track section is unoccupied.

Inductance coils 32 and 33 are illustrated as being disposed adjoining the track rails 10 and 11 adjacent the connection points 34 and 35 respectively so as to be energized by current flowing in a track circuit at these points. When there is no train in the vicinity of the points 34 and 35, there is very little current induced in the windings 32 and 33, and thus the relay TRB is normally deenergized under these conditions. When there is a train in the vicinity of the coils 32 and 33 so as to cause a voltage to be induced therein due to current flowing in the track rails at the point where the coils are disposed an input is provided for a frequency F2 Filter 36 through the coils 32 and 33 connected in series. An output of frequency F2 Filter 36 is applied to an Amplifier 37, and in accordance therewith, there is sufficient output of the Amplifier 37 to pick up track relay TRB. With relay TRB in its picked up position, a circuit can be closed for the energization of lamp GEl, even though the presence of a train in an adjoining track section has dropped the interrail potential to a point where the relay TRA becomes dropped away. The circuit for the energization of lamp GEI under such conditions includes back contact 38 of relay TRA and front contact 39 of 4relay TRB. For a condition where the associated track section is occupied by a train, relays TRA and TRB are both in their dropped away positions, and under these conditions occupancy in the associated track circuit is registered by the deenergization of lamp GEl and the energization of lamp REl through back contacts 38 and 39 of relays TRA and TRB respectively.

With reference to FIG. 4, an embodiment of the present invention is illustrated as applied to the control of track circuits at a highway crossing without the use of insulated joints. According to conventional practice for high frequency highway crossing track circuits, track circuits of distinctive frequencies are fed from respective sides of the crossing, through the crossing, so that two track circuits have a common overlap section including the portion of the trackway at the highway crossing.

More specifically, with reference to FIG. 4, frequency F1 Transmitter 40 is connected across track rails 41 and 42 at a point in approach of the crossing of the highway H for eastbound traic, and similarly a frequency F2 Transmitter 43 is connected across the track rails 41 and 42 at a point to detect the approach to the highway H of westbound trains. Each of the transmitters is preferably connected to the track rails through a filter as described relative to the transmitters of FIG. 1 to minimize the loading of one track circuit by the transmitter of the other. A frequency F1 Receiver 44 is provided as a part of a track circuit fed by the frequency F1 Transmitter 40 and extending through the highway H, and similarly a frequency F2 Receiver 45 is provided for receiving frequency F2 from the Transmitter 43 in a track circuit extending through the highway H.

Although the method of connection of the Receivers 44 and `45 of FIG. 4 to the track rails 41 and 42 may be of one form or another in accordance Vwith the requirements of practice, it is assumed that connection is made as has been described relative to FIG. 2 wherein the interrail potential is applied to each receiver through the windings of associated induction coils. Thus the frequency F1 Receiver 44 is connected to track rails 41 and 42 through induction coils 46 and 47, respectively, and the frequency F2 Receiver 45 is connected to the track rails 41 and 42 through the coils 48 and 49.

The general mode of operation, according to FIG. 4, is that the transmitters 40 and 43 are both normally operating, and that the Receivers 44 and 45 have their track occupancy detection relays energized. The approach of an eastbound train to the crossing, for example, initiates operation of a warning signaling device (not shown) upon shunting the Transmitter F1 to cause a track relay of the frequency F1 Receiver 44 to be dropped away. After the train has progressed across the highway H, the track relay of the frequency F1 Receiver 44 becomes energized as soon as the rear of the train has passed the point of connection of the coils 46 and 47 to the rails 41 and 42 respectively. This energization becomes effective immediately after the last axle of the train has passed the point of connection of these coils to the rails 41 and 42 because relatively high current is flowing through the track rails at this time in the rear of the train in the track circuit energized by the transmitter 40. There is, therefore, sufiicient potential induced in the coils 46 and 47 to energize the track relay of frequency F1 Receiver 44, irrespective of there being a low interrail potential at this time because of the rail shunt applied by the passing train at a point just beyond the connection of the coils 46 and 47 to the rails 41 and 42.

From the above described mode of operation, it will be readily apparent that the use of the present invention as applied to the control of highway crossing signaling devices greatly facilitates the control of such devices by providing a more definite point in the trackway for extinguishing the signals after passage of a train, without requiring the use of rail joints.

One means, for example, that can be used for securing each of the induction coils, such as the coil 22, to the associated track rail is shown in FIG. 5. Coil 22 is illustrated as being secured to the rail 10 by a supporting bracket which has bifurcated side webs 60a for receiving a portion 61 of the rail flange. The bracket 60 is clamped to the flange of rail 10 by a hook bolt 62. Coil 22 is bolted to the bracket 60 by bolts 63 extending through the bracket 60 and the base of the `coil structure. The coil 22 has a lug 64 on the side adjoining the track rail through which studs 65 are threaded on each side of the coil 22. The studs 65 are secured against rotation by lock nuts 66. The studs 65 bear against the web 67 of the rail 10 and provide a support and adjustment for the alignment of the bracket 60.

Having thus described specific embodiments of the present invention as applied to different signaling conditions for the systems using continuous track rail, it is to be understood that these -forms have been chosen to facilitate the disclosure of the invention rather than to limit the number of forms the invention may assume, and it is to be further understood that various adaptations, alterations and modifications may be applied to the specific form shown in accordance with the requirements of practice within the spirit of the present invention except as limited by the appending claims.

What I claim is:

1. A double-rail wayside track circuit extending from a first point to a second point in a stretch of continuous rail railway track comprising, a source of alternating current connected across the track rails at said first point in said stretch of track, induction coils disposed adjacent the track rails respectively at said second point, each of the coils having its magnetic axis normal to the longitudinal axis of the associated track rails, and electroresponsive means connected across the track rails at said second point through windings of said induction coils respectively and through wires secured to the track rails, said electroresponsive means being operable to one condition in rcsponse to an interrail potential at said second point from said source and in response to the fiow of current from said source in the track rails when the rails are shunted at a point outside of a section between said first point and said second point, and said electroresponsive means being operable to another condition to register the presence lof a vehicle when the vehicle shunts the track rails between said fi-rst point and said second point in said stretch of railway track.

2. A track circuit according to claim 1 wherein said source of alternating current is at a frequency in the audio frequency range.

3. A double-rail wayside track circuit extending from a first point to a second point in a stretch of continuous rail railway track comprising, a high frequency source of energy connected across the track rails .at said first point, receiving means at the second point for receiving energy through the track rails from said high frequency source, induction coils at said second point secured along one side of the track rails respectively with their magnetic axes normal to the longitudinal axes of the associated track rails for generating a potential in response to the flow of current through the track rails from said source,

said receiving means comprising a frequency ilter having one input lead connected to one `of the track rails at said second point through the associated induction coil and a Wire secured to said one track rail, and having another input lead connected to the other of the track rails at said second point through the associated induction coil and a wire secured to said another track rail, said receiving means comprising an amplier for amplifying an output of said lter, and said receiving means comprising a binary device controlled to one condition or another in response to respective high or low outputs of said ampli- Iier respectively.

4. A track circuit according to claim 3 wherein said binary device is a relay that is picked up when there is 8 ated to its dropped away position when a train is present between said rst and second points in said stretch of track.

References Cited UNITED STATES PATENTS 2,224,395 12/1940 Kemrnerer 246-130 2,719,218 9/1955 Miller 246-130 3,035,167 5/1962 Luft 246-130 3,046,392 7/1962 Luft 246-130 3,267,281 8/1966 Buck 246-125 3,268,723 8/1966` Failor et al. 246-130 EVON C. BLUNK, Primary Examiner.

Ilo train between said rst and second points, and is actu- 15 STANLEY T- KRAWCZEWICZ Examiner- 

1. A DOUBLE-RAIL WAYSIDE TRACK CIRCUIT EXTENDING FROM A FIRST POINT TO A SECOND POINT IN A STRETCH OF CONTINUOUS RAIL RAILWAY TRACK COMPRISING, A SOURCE OF ALTERNATING CURRENT CONNECTED ACROSS THE TRACK RAILS AT SAID FIRST POINT IN SAID STRETCH OF TRACK, INDUCTION COILS DISPOSED ADJACENT THE TRACK RAILS RESPECTIVELY AT SAID SECOND POINT, EACH OF THE COILS HAVING ITS MAGNETIC AXIS NORMAL TO THE LONGITUDINAL AXIS OF THE ASSOCIATED TRACK RAILS, AND ELECTRORESPONSIVE MEANS CONNECTED ACROSS THE TRACK RAILS AT SAID SECOND POINT THROUGH WINDINGS OF SAID INDUCTION COILS RESPECTIVELY AND THROUGH WIRES SECURED TO THE TRACK RAILS, SAID ELECTRORESPONSIVE MEANS BEING OPERABLE TO ONE CONDITION IN RESPONSE TO AN INTERRAIL POTENTIAL AT SAID SECOND POINT FROM SAID SOURCE AND IN RESPONSE TO THE FLOW OF CURRENT FROM SAID SOURCE IN THE TRACK RAILS WHEN THE RAILS ARE SHUNTED AT A POINT OUTSIDE OF A SECTION BETWEEN SAID FIRST POINT AND SAID SECOND POINT, AND SAID ELECTRORESPONSIVE MEANS BEING OPERABLE TO ANOTHER CONDITION TO REGISTER THE PRESENCE OF A VEHICLE WHEN THE VEHICLE SHUNTS THE TRACK RAILS BETWEEN SAID FIRST POINT AND SAID SECOND POINT IN SAID STRETCH OF RAILWAY TRACK. 